A PLC (Programmable Logic Controller) unit in which a plurality of control units are fixed on a base has been conventionally used for a part of a system or the like constituted by FA devices. The front surface side of each control unit has a substantially rectangular shape when viewed from the front, and the control unit is fixed on the base such that the longitudinal direction thereof is made to be a vertical direction. The control units are fixed on the base side by side in the horizontal direction (the lateral direction of the rectangular shape of the front surface side).
Cables such as power supply lines are sometimes connected to the front surface of the control units. Among those control units, the one whose front surface is covered with a cover designated to open and close is disclosed in, for example, Patent Literature 1.